System for stabilizing a portion of the spine

ABSTRACT

A system for stabilizing a portion of the spine comprising an elongate plate attached to one or more vertebrae by a number of bone anchors, with the system including one or more features that provide visualization of an implant disposed within a vertebral space and/or the interface between the implant and the adjacent vertebral tissue. A holding instrument is included that is engageable to the plate for positioning the plate adjacent the spinal column.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.12/983,349, filed on Jan. 3, 2011, which is itself a continuation ofU.S. application Ser. No. 10/603,471, filed on Jun. 25, 2003, now U.S.Pat. No. 7,862,597, which claims the benefit of the filing dates of U.S.Provisional Application Ser. No. 60/405,360, filed on Aug. 22, 2002, andU.S. Provisional Application Ser. No. 60/422,298 filed on Oct. 30, 2002,the contents of each of which are hereby incorporated by reference intheir entirety.

BACKGROUND

The invention generally relates to systems for treatment of the spine,and more particularly to systems for stabilizing a portion of the spinefor the treatment of various spinal pathologies.

While attempts have been made to develop spinal stabilization systemsthat address some of the needs and requirements for stabilization and/orfixation of the spine, there still remains a need for improved systemsand methods. For example, stabilization systems and methods sometimesutilize an interbody fusion device, such as a bone graft, which isinserted within the intervertebral disc space between adjacent vertebraeto promote bony fusion. An elongate plate is typically attached to thevertebrae to provide temporary stabilization during the fusion process.

Placement and attachment of the elongate plate to the spine can behindered since the plate and/or the instruments provided for placementand attachment can obscure visualization of the surgical site once theplate is positioned adjacent the vertebrae. As a result, verification ofplacement of the plate and/or the interbody fusion device requiresadditional x-rays or utilization of other radiographic imagingtechniques. The present invention attempts to eliminate or minimizethese verification requirements, to provide the surgeon with addedconfidence regarding proper placement of the plate and/or the interbodyfusion device, to reduce the time required to place the plate and/or theinterbody fusion device, and/or to minimize the patient's exposure toradiation.

Thus, there is a general need in the industry to provide improvedsystems for stabilizing a portion of the spine.

SUMMARY

The present invention relates generally to a system for stabilizing aportion of the spine. Certain forms of the invention that arecharacteristic of the embodiments disclosed herein are described brieflyas follows.

A system for stabilizing a portion of the spine is provided, comprisingan elongate plate attached to one or more vertebrae by a number of boneanchors, with the system including one or more features that providevisualization of an implant disposed within a vertebral space and/or theinterface between the implant and adjacent vertebral tissue.

In one aspect, the visualization feature comprises at least onevisualization opening to formed through the elongate plate.

In another aspect, the visualization feature comprises providing atleast one portion of the elongate plate with a reduced lateral profile.

In another aspect, the visualization feature comprises forming at leasta portion of the elongate plate from a translucent material.

In another aspect, the visualization feature comprises forming at leasta portion of the elongate plate from a radiolucent material.

In another aspect, the visualization feature comprises forming theelongate plate from a plurality of modular components.

In another aspect, the visualization feature comprises providing amethod of attaching the elongate plate to the vertebrae which minimizesinterference with visualization of the implant and/or the interfacebetween the implant and adjacent vertebral tissue.

In another aspect, the visualization feature comprises instrumentationfor attaching the elongate plate to the vertebrae which minimizesinterference with visualization of the implant and/or the interfacebetween the implant and adjacent vertebral tissue.

Further objects, features, advantages, benefits, and further aspects ofthe present invention will be apparent from the drawings and descriptioncontained herein.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a spinal stabilization system.

FIG. 2 is a side elevational view of the spinal stabilization systemshown in FIG. 1.

FIG. 3 is a top plan view of one embodiment of an elongate plate for usein association with the spinal stabilization system shown in FIG. 1.

FIG. 4 is a cross-sectional view of the elongate plate shown in FIG. 3,as viewed along line 4-4 of FIG. 3.

FIG. 5 is a cross-sectional view of the elongate plate shown in FIG. 3,as viewed along line 5-5 of FIG. 3.

FIG. 6 is a side elevational view of one embodiment of a fixed-anglebone screw for use in association with the spinal stabilization systemshown in FIG. 1.

FIG. 7 is a side elevational view of one embodiment of a variable-anglebone screw for use in association with the spinal stabilization systemshown in FIG. 1.

FIG. 8 is a side elevational view of one embodiment of a self-drillingbone screw for use in association with the spinal stabilization systemshown in FIG. 1.

FIG. 9 is an exploded partial side elevational view of one embodiment ofa retaining device for use in association with the spinal stabilizationsystem shown in FIG. 1.

FIG. 10 is a cross-sectional view of the retaining device shown in FIG.9 partially secured to the plate, as viewed along line 10-10 of FIG. 9.

FIG. 11 is a partial cross-sectional view of the spinal stabilizationsystem shown in FIG. 1, as engaged to a vertebra using the fixed-anglebone screw shown in FIG. 6.

FIG. 12 is a partial cross-sectional view of the spinal stabilizationsystem shown in FIG. 1, as engaged to a vertebra using thevariable-angle bone screw shown in FIG. 7.

FIG. 13 is a top plan view of the spinal stabilization system shown inFIG. 1, as engaged to a plurality of vertebrae.

FIG. 14 is a top plan view of another embodiment of an elongate platefor use in association with the spinal stabilization system of FIG. 1.

FIG. 15 is a top plan view of another embodiment of an elongate platefor use in association with the spinal stabilization system of FIG. 1.

FIG. 16 is a top plan view of another embodiment of an elongate platefor use in association with the spinal stabilization system of FIG. 1.

FIG. 17 is a top plan view of another embodiment of an elongate platefor use in association with the spinal stabilization system of FIG. 1.

FIG. 18 is an elevational view of a holding instrument engageable to aplate to facilitate positioning of the plate at the operative site.

FIG. 19 is an elevational view of a distal portion of the holdinginstrument of FIG. 18.

FIG. 20 is a sectional view through line 20-20 of FIG. 19.

FIG. 21 is a section view through line 21-21 of FIG. 19.

FIG. 22 is a plan view of a second member comprising a portion of theholding instrument of FIG. 18.

FIG. 23 is a section view through line 23-23 of FIG. 22.

FIG. 24 is a section view through line 24-24 of FIG. 23.

FIG. 25 is an elevational view of another embodiment holding instrumentincluding a guide mechanism.

FIG. 26 is a perspective view of the holding instrument of FIG. 25secured to a plate.

FIG. 27 is an elevational view of a distal portion of the holdinginstrument of FIG. 26 secured to a plate and a bone engaging fastenerbeing guided through the plate with the guide mechanism.

FIG. 28 is a perspective view of another embodiment holding instrumentincluding a guide mechanism.

FIG. 29 is an end view of a distal portion of the holding instrument andguide mechanism of FIG. 28.

FIG. 30 is a bottom plan view of the distal portion of the holdinginstrument and guide mechanism of FIG. 28.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is hereby intended, such alterations and further modificationsin the illustrated devices, and such further applications of theprinciples of the invention as illustrated herein being contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

Referring to FIGS. 1 and 2, shown therein is a spinal stabilizationsystem 20 according to one form of the invention for use in stabilizingat least a portion of the spinal column. In one embodiment,stabilization system 20 is generally comprised of an elongate plate 22positionable along a portion of the spinal column, a number of boneanchors 24 adapted to anchor plate 22 to the spinal column, and a numberof retaining devices 26 adapted to engage the bone anchors 24 to preventthe bone anchors 24 from loosening and backing out of plate 22.

In one embodiment, stabilization system 20 is configured for attachmentto the cervical region of the spinal column, spanning across a number ofcervical vertebrae. However, it should be understood that stabilizationsystem 20 may also be utilized in other areas of the spinal column, suchas the thoracic, lumbar, lumbo sacral and sacral regions of the spine.It should also be understood that stabilization system 20 can extendacross any number of vertebrae, including a pair of adjacent vertebraeor three or more vertebrae. Additionally, although stabilization system20 is illustrated and described as having application in an anteriorsurgical approach, stabilization system 20 may alternatively be appliedin other surgical approaches, such as, for example, antero-lateral,oblique and posterior surgical approaches.

In the illustrated embodiment, plate 22 extends along a longitudinalaxis 21 and is sized to span a distance between at least two vertebrallevels. However, it should be understood that plate 22 can take on otherconfigurations, such as, for example, any type of elongate elementsuitable for use in stabilizing a portion of the spine. It should alsobe understood that any number of plates 22, including a pair of plates22, may be used to provide stabilization to the spinal column. In oneembodiment of the invention, plate 22 is formed of a metallic materialsuch as, for example, stainless steel or titanium. However, it should beunderstood that plate 22 may be formed from a number of materialsincluding, for example, a pure metallic composition, a metallic alloy, ashape-memory alloy, a polymer material, a synthetic material, a biologicmaterial, and/or a resorbable material. Plate 22 is secured to cervicalvertebrae 600 (FIGS. 11-13) by a plurality of the bone anchors 24. Inone embodiment, bone anchors 24 are configured as bone screws. However,other types of bone anchors are also contemplated, such as, for example,bolts, hooks or other types of devices suitable for attaching plate 22to vertebrae 600. Retaining devices 26 engage adjacent pairs of bonescrews 24 to prevent the bone screws 24 from loosening and backing out.Retaining devices 26 may also be used to further secure plate 22 to thecervical vertebrae 600. In the illustrated embodiment, retaining device26 includes a fastener that engages plate 22 and abuts against the headsof adjacent bone screws 24. However, other types of retaining devicesare also contemplated, such as, for example, a pop rivet, a retainer, alock washer rotatably displaceable between an unlocked position and alocked position, an expansion screw positioned in the head of the boneanchor to expand the head of the bone anchor, a retaining elementintegrally formed with the plate, or any other type of retainingelement, device, mechanism or system. The retaining devices can bepositioned on the plate to retain a single bone anchor or multiple boneanchors.

Referring to FIGS. 3-5, shown therein are further details regardingplate 22. Plate 22 includes multiple nodes or connection portions 32that are configured to engage bone anchors 24 to attach plate 22 acrossmultiple vertebral levels. The connection portions 32 are separated fromone another by intermediate portions 34. Plate 22 has opposite endsurfaces 36, 38, opposite side surfaces 40, 42, and opposite upper andlower surfaces 44, 46. The corners of plate 22 between end surfaces 36,38 and side surfaces 40, 42 are rounded to eliminate sharp or abruptedges that could pinch, cut or wear against tissue. The corners of plate22 between upper surface 44 and the end and side surfaces 36, 38, 40 and42 are also rounded to eliminate sharp or abrupt edges that could pinch,cut or wear against tissue.

When plate 22 is attached to the spinal column (FIGS. 11 and 12), thelower surface 46 abuts an outer vertebral surface. In one embodiment,lower surface 46 of plate 22 defines a concave lateral curvature 610(FIG. 5) which corresponds to the anatomical lateral curvature of thevertebra 600. Lower surface 46 may also define a concave curvature 612(FIG. 4) extending along longitudinal axis 21 which corresponds to thenormal lordotic curvature of vertebra 600. In one embodiment, uppersurface 44 of plate 22 defines a convex curvature that substantiallycorresponds to the concave curvatures 610, 612 of lower surface 46 toreduce the amount of trauma to the adjacent soft tissue when plate 22 issecured to the vertebrae 600 and to reduce the overall profile of plate22. It should be understood, however, that plate 22 can take on otherconfigurations to accommodate the specific spinal anatomy and pathologyinvolved in the particular application of stabilization system 20.

In one embodiment, side surfaces 40, 42 of plate 22 adjacent theconnection portions 32 have a convex configuration, while side surfaces40, 42 adjacent intermediate portions 34 have a concave configuration.As a result, side surfaces 40, 42 have a serpentine shape or corrugatedconfiguration defining a series of alternating ridges or peaks 50 andgrooves or valleys 52. In the illustrated embodiment, each of the peaks50 and valleys 52 has an arcuate shape so as to form an undulating curveor sinusoidal pattern extending along longitudinal axis 21. The roundedconfiguration of peaks 50 and valleys 52 minimizes stress concentrationsand eliminates sharp or abrupt edges that could pinch, cut or wearagainst tissue. It should be understood, however, that peaks 50 andvalleys 52 can take one other shapes and configurations, such as, forexample, a triangular or rectangular shape so as to define a zigzag ortooth-like configuration.

In one embodiment of the invention, the upper and lower end surfaces 36,38 of plate 22 define oppositely facings recessed areas 54 and 56,respectively. The recessed areas 54, 56 may be used to position andorient various types of instruments, templates, guides or other devicesrelative to plate 22. For example, recessed areas 54, 56 may beconfigured to receive a corresponding portion of a plate holder, drillguide and/or a screw guide to ensure proper positioning and orientationof the guide relative to plate 22. It should be understood that recessedareas 54, 56 need not necessarily be defined in end surfaces 36, 38, butmay be defined in other portions of the elongate plate 22, such as, forexample, the side surfaces 40, 42 or upper surface 44.

In one embodiment, connection portions 32 are spaced from one another bya distance 620 that substantially corresponds to the spacing between theadjacent cervical vertebrae to which plate 22 is attached (FIG. 13).Although connection portions 32 are illustrated as being offset from oneanother by a uniform distance 620, it should be understood that in otherembodiments connection portions 32 may be offset from one another bynon-uniform distances. As should be appreciated, intermediate portions34 are spaced so as to be positioned adjacent a respectiveintervertebral disc space when plate 22 is attached to the cervicalvertebrae (FIG. 13).

In one embodiment, plate 22 defines a first width 630 adjacent theconnection portions 32 and a reduced second width 632 adjacent theintermediate portions 34. The reduced width 632 adjacent intermediateportions 34 decreases the outer contour and size of plate 22 to minimizethe lateral extent of plate 22 in the area adjacent the intervertebraldisc space. Additionally, the reduced width 632 adjacent intermediateportions 34 provides an area of reduced material to facilitate bendingof plate 22 as may be required to conform plate 22 to the particularspinal anatomy to which plate 22 is attached.

In one embodiment, plate 22 includes a number of visualization openingsor windows 60 extending through intermediate portions 34 between upperand lower surfaces 44, 46. Visualization openings 60 extend generallyalong longitudinal axis 21 of plate 22 and are generally positioned inthe area adjacent the intervertebral disc space when plate 22 isattached to the cervical vertebrae (FIG. 13). Intermediate portion 34includes a first member 61 extending along one side of visualizationopening 60 and a second member 63 extending along the opposite side ofvisualization opening 60. In one embodiment, visualization openings 60have an elongate hourglass-like configuration extending along virtuallythe entire length of the intermediate portions 34 and across asubstantial portion of the width of the intermediate portions 34.However, it should be understood that other embodiments contemplateother sizes and shapes for the visualization openings 60.

In the illustrated embodiment, visualization openings 60 include a pairof opposite side walls 62, 64 extending between a pair of opposite endwalls 66, 68. In one embodiment, side walls 62, 64 have a convex arcuateconfiguration that substantially corresponds to the outer contour ofside surfaces 40, 42 defined along the intermediate portions 34 of plate22. In this manner, the material width 634 of members 61, 63 between theouter side surfaces 40, 42 of the intermediate portions 34 and the sidewalls 62, 64 of the visualization openings 60 is substantially uniform.As a result, the elongate plate 22 is configured to provide optimumvisualization capabilities via the inclusion of relatively largevisualization openings 60 in combination with a reduced lateral profilein the areas adjacent the intermediate portions 34. The substantiallyuniform material width 634 provides plate 22 with sufficient loadbearing strength while minimizing stress concentrations.

Visualization openings 60 define a minimum width 636 transversely tolongitudinal axis 21. In one embodiment, width 636 is unobstructed andat least as great as the combined widths 634 of first and second members61, 63 to provide optimal visualization capabilities throughvisualization opening 60 and around the sides of plate 22. Accordingly,visualization capabilities through plate 22 and on either side of plate22 are enhanced. For example, unobstructed width 636 can range from 100percent to about 150 percent of the combined widths 634 of first andsecond members 61, 63. In another example, unobstructed width 636 canrange from 100 percent to about 125 percent of the combined widths 634of first and second members 61, 63. Other embodiments contemplate anunobstructed width 636 that is less than the combined widths 634 offirst and second members 61, 63. For example, unobstructed width 636 canrange from 50 percent to less than 100 percent of the combined widths634 of first and second members 61, 63. In another example, unobstructedwidths 636 can range from 75 percent to less than 100 percent of thecombined widths 634 of first and second members 61, 63.

In the illustrated embodiment, end walls 66, 68 of the visualizationopenings 60 have a concave arcuate configuration to maximize the size ofthe visualization openings 60 while maintaining sufficient load bearingstrength of the plate 22. In one embodiment, visualization openings 60have a maximum length along longitudinal axis 21 that allows viewing ofthe bony structure of the adjacent vertebrae therethrough. The cornersformed between side walls 62, 64 and end walls 66, 68 are rounded tominimize stress concentrations and to eliminate sharp or abrupt edgesthat could pinch, cut or wear against tissue. Although visualizationopenings 60 have been illustrated with a particular shape andconfiguration, it should be understood that other embodimentscontemplate other shapes and configurations of visualization openings60, such as, for example, a rectangular, elliptical or circularconfigurations, convexly curved side walls and convexly curved endwalls, concavely curved side walls and concavely curved end walls,convexly curved end walls and concavely curved side walls, andcombinations thereof.

In one embodiment, each of the connection portions 32 includes a pair ofbilateral openings 70, 71 configured to receive a respective pair ofbone anchors 24 therein. The bone anchor openings 70, 71 extend entirelythrough plate 22 between the upper and lower surfaces 44, 46 and aredisposed on opposite sides of longitudinal axis 21. Bone anchor openings70, 71 are arranged along an axis 72, 73, respectively. In theillustrated embodiment, axes 72, 73 are inwardly tapered toward oneanother at an angle 640 (FIG. 5) relative to a transverse axis 23defined through plate 22. Additionally, bone anchor openings 70, 71extending through the outermost connection portions 32 (e.g. adjacentthe end surfaces 36, 38) are outwardly tapered at an angle 642 (FIG. 4).In one embodiment, angle 640 is approximately 6 degrees and angle 642 isapproximately 12 degrees. However, other angles 640, 642 are alsocontemplated.

Although the illustrated embodiment of plate 22 depicts each of theconnection portions 32 as including a pair of bilateral bone anchoropenings 70, 71, it should be understood that other configurations andarrangements are also contemplated. For example, each of the connectionportions 32 may alternatively define a single bone anchor opening orthree or more bone anchor openings. It should also be understood thatthe bone anchor openings 70, 71 need not necessarily extend though eachof the connection portions 32, but may alternatively extend throughselect ones of the connection portions 32. It should also be understoodthat the bone anchor openings 70, 71 need not necessarily be arranged ina bilateral configuration, but may alternatively be arranged in otherconfigurations, such as, for example, an axially offset configuration.

Aside from angular orientation, bone anchor openings 70, 71 arevirtually identical, each being sized and configured to accept acorresponding one of the bone anchors 24 therein, the details of whichwill be discussed below. Each of the bone anchor openings 70, 71includes a cylindrical-shaped portion 80 extending from the lowersurface 46, a spherical-shaped recess portion 82 extending from thecylindrical-shaped portion 80, and a conical portion 84 extending fromspherical-shaped recess portion 82 and opening onto upper surface 44. Inone embodiment, the conical portion 84 is outwardly flared atapproximately 45 degrees relative to the respective axes 72, 73.Although specific sizes and configurations of bone anchor openings 70,71 have been illustrated and described herein, it should be understoodthat other sizes and configurations are also contemplated.

Each of the connection portions 32 also includes an aperture 90configured to receive a respective one of the retaining devices 26therein, the details of which will be discussed below. The apertures 90extend through plate 22 between upper and lower surfaces 44, 46 and arepositioned generally along longitudinal axis 21 between a laterallyadjacent pair of bone anchor openings 70, 71. Each of the apertures 90includes a threaded portion 92 extending from the lower surface 46 ofplate 22 and a cylindrical-shaped countersunk portion 94 extending fromthe threaded portion 92 and opening onto upper surface 44. In oneembodiment, the countersunk portion 94 intersects and overlaps at leasta portion of each of the bone anchor openings 70, 71, and moreparticularly the spherical-shaped recess portion 82 of the bone anchoropenings 70, 71. Although a specific size and configuration of theretaining device apertures 90 has been illustrated and described herein,it should be understood that other sizes and configurations are alsocontemplated. For example, apertures 90 need not necessarily extendentirely through plate 22, but may alternatively extend partiallythrough plate 22 without penetrating lower surface 46. Apertures 90 mayalso be elongated to accept a retaining device longitudinally slidableor movable along or relative to plate 22.

Referring to FIG. 6, shown therein is one embodiment of a bone screw 24suitable for use in association with spinal stabilization system 20.Bone screw 24 is of the fixed-angle type, the significance of which willbecome apparent below. Bone screw 24 includes a head portion 100connected to a threaded shank portion 102 by an intermediate portion104. Threaded shank portion 102 defines a number of threads 106configured to engage vertebral bone and is sized to pass through thecylindrical-shaped portion 80 of bone anchor openings 70, 71 definedthrough plate 22. Threads 106 are adapted to engage cortical and/orcancellous bone. In one embodiment, bone screw 24 is configured as aself-tapping screw. In another embodiment, bone screw 24 is configuredas a self-drilling screw. Threads 106 gradually transition intointermediate portion 104 by way of a thread run out 108.

Intermediate portion 104 of bone screw 24 has an outer diameter 650 thatis slightly smaller than the inner diameter of the cylindrical-shapedportion 80 of bone anchor openings 70, 71. Head portion 100 includes aspherical-shaped surface 110 that is substantially complementary to thespherical-shaped recess portion 82 defined by bone anchor openings 70,71. Head portion 100 additionally includes a truncated or flattenedupper surface 112 through which extends a tool receiving recess 114configured to receive a driving tool therein (not shown). In oneembodiment, tool receiving recess 114 is a hexagonal recess. However,other shapes and configuration of tool receiving recesses are alsocontemplated.

Referring to FIG. 7, shown therein is another embodiment of a bone screw25 suitable for use in association with spinal stabilization system 20.Bone screw 25 is of the variable-angle type, the significance of whichwill become apparent below. Variable-angle bone screw 25 is configuredsimilar to fixed-angle bone screw 24, including a head portion 120connected to a threaded shank portion 122 by an intermediate portion124. Threaded shank portion 122 defines a number of threads 126configured to engage vertebral bone. Like fixed-angle bone screw 24,variable-angle bone screw 25 may also be configured as a self-tappingand/or a self-drilling screw. However, unlike intermediate portion 104of bone screw 24, intermediate portion 124 of bone screw 25 has an outerdiameter 652 that is significantly smaller than the inner diameter ofthe cylindrical-shaped portion 80 of bone anchor openings 70, 71, thesignificance of which will be discussed below. Head portion 120 includesa spherical-shaped surface 130 that is substantially complementary tothe spherical-shaped recess portion 82 defined by the bone anchoropenings 70, 71. Head portion 120 also includes a truncated or flattenedupper surface 132 through which extends a tool receiving recess 134configured to receive a driving tool therein (not shown).

Referring to FIG. 8, shown therein is another embodiment of a bone screw700 suitable for use in association with spinal stabilization system 20.Bone screw 700 is of the self-drilling fixed angle type. Bone screw 700can also be provided with variable angle capabilities as discussed abovewith respect to bone screw 25. Self-drilling bone screw 700 includes ahead portion 720 connected to a threaded shank portion 722 by anintermediate portion 724. Threaded shank portion 722 defines a number ofthreads 726 configured to engage vertebral bone. Intermediate portion724 of bone screw 700 includes an outer diameter 752 that is sized tofit snugly in the bone anchor openings 70, 71 to provide a fixed anglerelative to the plate when seated in openings 70, 71. Intermediateportion 724 could also be provided with a significantly smaller diameterto provide variable angle placement capabilities. Head portion 720includes a spherical-shaped surface 730 that is substantiallycomplementary to the spherical-shaped recess portion 82 defined by thebone anchor openings 70, 71. Head portion 720 also includes a truncatedor flattened upper surface 732 through which extends a tool receivingrecess 734 configured to receive a driving tool therein (not shown). Thedistal tip of shank 722 includes a sharp point 728 to facilitatepenetration into bone, and a relieved portion 736 to facilitate passageinto the undrilled, untapped bony structure.

Referring to FIGS. 9 and 10, shown therein are various details regardingretaining device 26. In one embodiment, retaining device 26 is generallycomprised of a fastener 150 and a washer 152. Although a specificconfiguration of retaining device 26 has been illustrated and describedherein, it should be understood that other configurations of retainingdevices are also contemplated as discussed above.

Fastener 150 includes a head portion 154 and a threaded shank portion156 extending therefrom. Threaded shank portion 156 defines a number ofmachine threads 158 configured to engage threaded portion 92 of aperture90 defined by plate 22. Threaded shank portion 156 terminates in a sharppoint 160 to aid in the insertion of fastener 150 into threaded portion92 of aperture 90 and to facilitate penetration into vertebral bone.Head portion 154 includes an outwardly tapering conical surface 162. Inone embodiment, conical surface 162 defines a taper angle ofapproximately 45 degrees. Head portion 154 further includes an uppersurface 164 through which extends a tool receiving recess 166 configuredto receive a driving tool (not shown). In one embodiment, tool recess166 is a Phillips-type recess. However, other types and configurationsof tool receiving recesses are also contemplated.

Washer 152 has an outer surface including a lower tapered portion 170and an upper non-tapered portion 172. Washer 150 also defines an opening174 extending therethrough having a lower non-tapered portion 176 and anupper tapered portion 178. Upper tapered portion 178 is substantiallycomplementary to outer conical surface 162 of fastener 150. Engagementbetween outer conical surface 162 of fastener 150 and tapered portion178 of washer opening 174 facilitates self-centering of fastener 150within washer 152. Non-tapered portion 176 of washer opening 172 issized to receive threaded portion 156 of fastener 150 therethrough forengagement with threaded portion 92 of aperture 90 defined by plate 22.

Referring to FIG. 11, shown therein is plate 22 attached to a vertebra600 via the fixed-angle bone screws 24. Initially, plate 22 ispositioned along the spinal column so as to extend between at least twovertebrae, with lower surface 46 positioned in abutment against an outersurface of vertebra 600. Connection portions 32 of plate 22 are thensecured to the vertebra 600 by passing threaded portions 102 of bonescrews 24 through respective ones of the bone anchor openings 70, 71 anddriving threaded portions 102 into vertebral bone by way of a driver(not shown) engaged within the tool receiving recess 114 (FIG. 6).Conical portion 84 of bone anchor openings 70, 71 serves to facilitateinsertion of bone screws 24 into bone anchor openings 70, 71 and/or toaid in positioning and orientation of screw guides, drill guides, drillsor other instrumentation (not shown) relative to plate 22.

Once plate 22 is properly positioned and oriented relative to vertebra600, bone screws 24 are driven into vertebral bone until the lowerportion of the spherical surface 110 of screw head 100 is positioned inabutment against the spherical-shaped recess portion 82 of bone anchoropening 70, 71, with the intermediate portion 104 of the bone screw 24positioned within the cylindrical-shaped portion 80 of bone anchoropenings 70, 71. The relatively close tolerance between intermediateportion 104 of bone screw 24 and cylindrical-shaped portion 80 of boneanchor openings 70, 71 orients bone screws 24 at a fixed angle alongbone anchor axes 72, 73 and substantially prevents pivotal ortranslational movement of bone screws 24 relative to plate 22. Thespherical-shaped recess portions 82 also act as a countersink for headportions 100 of bone screws 24, thereby allowing a significant portionof screw heads 100 to be positioned beneath upper surface 44 of plate 22to minimize the overall height or profile of spinal stabilization system20.

Once bone screws 24 are fully driven into vertebra 600 and plate 22 issecurely attached to vertebra 600, retaining devices 26 are installed toprevent bone screws 24 from loosening and backing out of plate 22.Threaded shank portion 156 of fastener 150 is initially inserted throughnon-tapered portion 176 of opening 174 in washer 152. Threaded shankportion 156 is then threaded into threaded portion 92 of aperture 90 byway of a driver (not shown) engaged within tool receiving recess 166. Asfastener 150 is driven through threaded portion 92 of aperture 90,pointed end 160 penetrates into vertebral bone, thereby further securingelongate plate 22 to the vertebra 600. Additionally, by embeddingthreaded portion 92 within vertebral bone, fastener 150 is less likelyto loosen and back out of plate 22. Fastener 150 continues to bethreaded through the aperture 90 until lower conical surface 162 offastener head 154 engages tapered portion 178 of washer opening 174,which in turn engages outer conical surface 170 of washer 152 tightlyagainst the upper portion of spherical surface 110 of bone screw head100. Engagement of washer 152 against bone screw head 110 prevents bonescrews 24 from loosening and backing out of plate 22.

Referring to FIG. 12, shown therein is plate 22 attached to vertebra 600via variable-angle bone screws 25. Variable-angle bone screws 25 co-actwith plate 22 and retaining device 26 in a manner similar to thatdescribed above with regard to the fixed-angle bone screws 24. However,with regard to variable-angle bone screws 25, since intermediate bonescrew portion 124 is sized significantly smaller than cylindrical-shapedportion 80 of bone anchor openings 70, 71, a gap 654 exists between theintermediate bone screw portion 124 and plate 22. This gap 654 permitsbone screws 25 to pivot or toggle within the bone anchor openings 70, 71relative to the bone anchor axes 72, 73, thereby allowing bone screws 25to be positioned at a variable angle relative to plate 22. It isunderstood that the degree of angulation of bone screws 25 is limited bythe size of gap 654 between the intermediate bone screw portion 124 andplate 22. In one embodiment, gap 654 is sized to permit angulation ofbone screws 25 up to 20 degrees in any direction relative to bone anchoraxes 72, 73. Other angulations for bone screws 25 are also contemplated,ranging from 0 degrees to 45 degrees, for example.

The variable-angle capability provided by bone screw 25 allows thesurgeon to engage bone screw 25 to the vertebra 600 at any angle withinthe defined angulation limits, thereby providing greater flexibility inorienting bone screws 25 at a select angle to accommodate the particularanatomy of the vertebra 600 and/or the pathology being treated.Moreover, this variable-angle capability provided by bone screws 25permits a limited degree of micro-motion or translation between bonescrews 25 and plate 22, which may prevent or at least reduce thebuild-up of load stresses within stabilization system 20. It should beunderstood that in certain embodiments, a combination of fixed-anglebone screws 24 and variable-angle bone screws 25 may be used to secureplate 22 to vertebra 600.

Referring to FIG. 13, shown therein is plate 22 attached to the cervicalregion of the spinal column. More particularly, plate 22 is sized tospan multiple vertebral levels, with the connection portions 32 attachedto a number of cervical vertebrae 601, 602, 603 via bone anchors 24, 25and/or the fasteners 150 of the retaining devices 26. When plate 22 issecured to vertebrae 601, 602, 603, intermediate portions 34 andvisualization openings 60 are positioned approximately adjacentrespective intervertebral disc spaces 606, 607. Additionally, thereduced width 632 of intermediate portions 34 relative to the connectionportions 32 provides plate 22 with a reduced lateral profile in theareas adjacent the intervertebral disc spaces 606, 607.

Visualization openings 60 and the reduced lateral profile of theintermediate portions 34 of plate 22 provide the capability to visualizethe intervertebral disc spaces 606, 607 and/or spinal implants 660 orother devices or instruments positioned within the intervertebral discspaces 606, 607. More specifically, these features provide for directvisualization of implants 660 disposed within the intervertebral discspaces 606, 607, the relationship between plate 22 and implants 660,and/or the interface between implants 660 and the vertebral endplates.As mentioned above, such implants 660 may include, for example, a bonegraft, an artificial fusion device, or any other type of interbodydevice that is insertable within the intervertebral disc space. Furtherexamples of such implants include bone dowels, push-in type cages,screw-in type cages, tapered cages, cages filled with bone graft and/orgraft substitute material or other types of devices suitable for fusionapplications, external or internal stabilization of a segment of thespinal column or other types of bony segments.

It should be understood that stabilization system 20 can be used inconjunction with fusion-type implants that promote fusion betweenadjacent pairs of vertebrae and/or spacer-type implants that serve tomaintain a spacing between adjacent pairs of vertebrae. In applicationsinvolving fusion type implants, plate 22 provides temporarystabilization during the fusion process. Following fusion of theadjacent vertebrae, plate 22 may be removed from the patient, may bemaintained within the patient, or may be formed of a resorbable materialthat is resorbed into the patient over a period of time.

In the illustrated embodiment shown in FIG. 13, a single implant 660 iscentrally disposed within each of the intervertebral disc space 606,607. In this case, visualization openings 60 provide the primary meansfor direct visualization of implants 660 in relation to theintervertebral disc spaces 606, 607. However, in other embodiments, apair of implants 660 may be inserted bilaterally within each of theintervertebral disc space 606, 607. In this instance, the reducedlateral profile of the intermediate portions 34 of plate 22 provides anadditional feature for direct visualization of implants 660 in relationto vertebrae 601, 602, 603 and intervertebral disc spaces 606, 607.

The direct visualization capabilities offered by plate 22 eliminates, orat least minimizes, the need to verify intra-operative or post-operativeplacement and positioning of implants 660 within intervertebral discspaces 606, 607 (e.g., verification of the interface between the implantand the vertebral endplates, the lateral positioning of the implantwithin the disc space, the relationship between the implant and theelongate plate, etc.). As a result, the need for additional x-rays orother radiographic imaging techniques is significantly reduced, therebyminimizing the patient's exposure to radiation. Likewise, the timerequired to implant plate 22 and/or the implants 660 is alsosignificantly reduced. Additionally, the surgeon is provided with addedconfidence regarding the proper placement of plate 22 and/or theimplants 660 relative to vertebrae 601, 602, 603 and intervertebral discspaces 606, 607.

Other embodiments provide visualization features in place of or inaddition to those features illustrated and described above with regardto spinal stabilization system 20. For example, a plate may be providedthat is at partially formed from a translucent material to providedirect visualization of one or more implants disposed withinintervertebral disc spaces, the relationship between the plate and theimplants, and/or the interface between the implants and the vertebralendplates. In one embodiment, the entire plate may be formed of atranslucent material. In another embodiment, only the portions of theplate that are positioned approximately adjacent the intervertebral discspace are formed of a translucent material, with the remainder of theplate, including the portions that are connected to the vertebrae,formed of conventional materials such as stainless steel or titanium. Itshould be understood that a variety of materials may be used to providevisualization capabilities to the plate, including various types oftranslucent materials, partially-translucent materials, transparentmaterials, semi-transparent materials, or any other material that allowa sufficient amount of light to pass therethrough. Such materialsinclude, for example, various types of plastic materials or polymericmaterials.

In another embodiment, the plate may be designed to have a modularconfiguration to provide visualization of the implant and/or thevertebral anatomy during placement of the plate and/or the implant. Forexample, select portions of the plate may be removed to provide directvisualization capabilities at various stages of the implant/plateplacement procedure. The removed portions may be subsequently replacedor obscured after the placement procedure is complete. For example,certain portions of the plate positioned adjacent the intervertebraldisc space may be configured for selective removal to provide enhancedvisualization of the implant and/or the vertebral anatomy at variousstages of the implant/plate placement procedure. The removable portionsmay subsequently be reassembled with the remainder of the plate tostrengthen the plate and/or to conceal, cover or otherwise obscure thevisualization site.

Although the above-discussed embodiments provide direct visualizationcapabilities involving viewing with the naked eye, it should beunderstood that other means and/or methods may be used to provideindirect visualization capabilities in place of or in addition to thedirect visualization capabilities discussed above. For example, a platemay be provided which is at partially formed from a radiolucent materialto provide indirect visualization via the use of x-rays or otherradiographic imaging techniques. In one embodiment, the entire plate maybe formed of a radiolucent material. In another embodiment, only theportions of the plate that are positioned adjacent the intervertebraldisc space are formed of a radiolucent material, with the remainder ofthe plate, including the portions that are connected to the vertebrae,formed of conventional materials such as stainless steel or titanium.

Various techniques, devices and instrumentation are provided to positionthe plate in relation to the vertebrae and to engage the plate to thevertebrae. These techniques, devices and instrumentation are designedand/or configured in such a manner as to minimize interference with thevisualization capabilities provided by the plate and/or to provideindependent visualization capabilities.

In one embodiment, self-drilling bone screws may be used to secure theplate to the vertebrae, thereby eliminating use of a drill guide whichcould potentially interfere with the visualization capabilities providedby the plate. In another embodiment, the instrumentation used toposition and attach the plate to the vertebrae may be formed frommaterials that provide some degree of visualization. Suchinstrumentation may include, for example, templates, plate holders, bonescrew guides, drivers, or other instruments or devices typicallyassociated with the placement and attachment of a plate to a number ofvertebrae. In one embodiment, various portions of the instrumentationmay be formed of a translucent material or a radiolucent material toprovide enhanced visualization capabilities to the spinal fixationsystem. In another embodiment, the design of the instrumentation maytake into account various geometric considerations that provide enhancedvisualization capabilities and minimization of interference with thevisualization capabilities provided by the plate.

Referring to FIGS. 14 and 15, shown therein are plates 200 and 300,respectively, according to other embodiments of the stabilization system20. Plates 200 and 300 are configured similar to plate 22 illustratedand described above. However, the connection portions 32 of plate 200are spaced from one another by a distance 621 which is less thandistance 620 separating connection portions 32 of plate 22. As a result,the visualization openings 60 defined by plate 200 have a lesserlength-to-width aspect ratio than do visualization openings 60 definedby plate 22. With regard to plate 300, the connection portions 32 arespaced from one another by a distance 622, which is greater thandistance 620 separating connection portions 32 of plate 22. As a result,visualization openings 60 defined by plate 300 have a greaterlength-to-width aspect ratio than do visualization openings 60 definedby plate 22.

As should be appreciated, the distance separating connection portions 32of plates 22, 200 and 300 may be selected to match the particularspacing between the vertebrae to which the plates are attached. Asshould also be appreciated, the connection portions 32 may be spacedapart so as to position the intermediate portions 34 of the plateadjacent respective ones of the intervertebral disc spaces. It shouldalso be appreciated that the distance separating adjacent pairs of theconnection portions 32 need not necessarily be uniform. Instead, thedistance separating adjacent pairs of connection portions 32 can beselected to accommodate the particular spinal anatomy to which the plateis attached.

Referring to FIGS. 16 and 17, shown therein are plates 400 and 500,respectively, according to other embodiments of the stabilizationsystem. Plates 400 and 500 are configured similar to plate 22illustrated and described above. However, unlike plate 22 which includesthree connection portions 32 for attachment across three vertebrallevels, plate 400 includes four connection portions 32 for attachmentacross four vertebral levels, while plate 500 includes a pair ofconnection portions 32 for attachment across two vertebral levels. Asshould be appreciated, the plates used in association with the presentinvention can be readily adapted to span any number of vertebral levelsby appropriately sizing plate 22 and by providing plate 22 with theappropriate number of connection portions 32.

Various length-to-width aspect ratios for visualization openings arecontemplated to provide optimal visualization capabilities. In someembodiments, such as shown in FIG. 14, length 638 is less than the width636 of visualization opening 60 due to the overall length constraintsfor the plate imposed by anatomical considerations. Length-to-widthaspect ratios ranging from 0.5 to 1.0 are contemplated for theseembodiments. In other embodiments, the maximum length 638 to minimumwidth 636 aspect ratios of visualization openings 60 the plate aregreater than 1.0. In some embodiments, length-to-width aspect ratios of1.0 to about 2.5 are contemplated. Other embodiments contemplatelength-to-width aspect ratios ranging from about 1.0 to about 1.5. Stillother embodiments contemplate length-to-width aspect ratios ranging fromabout 1.5 to about 2.25. Further embodiments contemplate length-to-widthaspect ratios ranging from about 1.0 to about 2.0.

Referring to FIG. 18 there is shown a holding instrument 500 for holdinga plate, such as any of the plate embodiments discussed herein, forpositioning the plate adjacent to the spinal column. Holding instrument500 assists the surgeon in maintaining the position of the plate as boneengaging fasteners or anchors are positioned through the plate holes.Holding instrument 500 includes a holding system 506 at a distal end ofan actuating system 501. A locking system 508 is provided to maintainholding system 506 in engagement with the plate or other implant.

Actuating system 501 includes a handle system 502 and a connectingsystem 504 operable to move holding system 506 between a positionengaged or clamped with the plate and a position released from theplate. Handle system 502 includes a first handle portion 510 and asecond handle portion 516 pivotally secured to a frame portion 511 offirst handle portion 510. Connecting system 504 includes a first member512 coupled at its proximal end to frame portion 511 of first handleportion 510, and a second member 513 coupled at its proximal end 546(FIG. 22) to frame portion 511 of first handle portion 510. As furthershown in FIGS. 19 and 21, first member 512 includes a channel 517therethrough for receiving a linkage 514. Linkage 514 is pivotallycoupled at its proximal end to second handle portion 516 and movablerelative to first and second members 512, 513 in channel 517 in responseto movement of second handle portion 516 relative to first handleportion 510. Movement of linkage 14 manipulates holding system 506between a clamped or engaged position and a release position.

Holding system 506 includes a first holding member 530 (FIGS. 19 and 20)and a second holding member 540 (FIGS. 22-24.) In the illustratedembodiment, second holding member 540 is at located at the distal end ofsecond member 513 and integral therewith. A receptacle 549 is formed insecond member 513 and proximally located relative to holding member 540.It is further contemplated that, as shown in FIG. 23, second holdingmember 540 can extend relative to a proximal portion of second member513 at an angle 543 to facilitate engagement of the plate at a desiredangular orientation relative to longitudinal axis 505 of holdinginstrument 500.

First holding member 530 includes a proximal portion 531 pivotallycoupled to a distal end of linkage 514 via pin 533. Proximal portion 531can be provided with a reduced width that allows proximal portion 531 tobe received in receptacle 549. Proximal portion 531 further includes abore 535 to receive a pin to pivotally couple proximal portion 531 withbore 548 in receptacle 549 of second member 513. First holding member530 is thus pivotal relative to second member 513 via actuation oflinkage 514 with handle portion 516 while second holding member 540remains in a fixed position.

Reciprocation of linkage 514 with handle system 502 moves linkage 514 infirst member 512 and thus first holding member 530 between first andsecond positions relative to second holding member 540. In the firstposition, such as shown in FIG. 18, first holding member 530 is pivotedaway from second holding member 540 for positioning of a portion of aplate or other implant therebetween. In the second position, such asshown in FIG. 27, first holding member 530 is moved toward secondholding member 540 for gripping or clamping the plate or implanttherebetween.

Holding system 506 can be adapted to provide secure gripping or clampingof the implant between holding members 530, 540. For example, as shownin FIG. 19-20, holding member 530 includes an engagement member 539having a distal flange 532, a proximal flange 534, and a contactingsurface 537 therebetween that includes a convex curvature transverse tolongitudinal axis 505 of holding instrument 500. When clamped to an endwall or end surface of plate 22, for example, distal flange 532 can bepositioned along bottom surface 46 of plate 22, while proximal flange534 can be positioned along upper surface 44 of plate 22. The convexlycurved contact surface 537 can match the concave surface profile of aplate surface against which it is to be positioned, such as end surface36 of plate 22. Plate 22 can include receptacles or recesses tofacilitate placement of holding members 530, 540 in the desired positionrelative to plate 22. For example, contact surface 537 can conform tothe curvature of recess 54 of plate 22.

Similarly, second holding member 540 includes an engagement member 541having a distal flange 544, a proximal flange 542, and a convexly curvedcontact surface 547. When clamped to an end wall or end surface of plate22, for example, distal flange 544 can be positioned along bottomsurface 46 the plate 22, and proximal flange 542 can be positioned alongupper surface 44 of plate 22. Contacting surface 547 can contact an endwall of plate 22, such as upper wall 66 of upper visualization openings60 or bottom end surface 38.

The convexly curved contact surfaces 537, 547 of holding members 530,540 provide an evenly distributed clamping force along the end wallengaged, and provide firm gripping of the end walls of the platetherebetween. It is contemplated that holding members 530, 540 couldalso be positioned relative to the plate to clamp, for example, endwalls 68, 66 of adjacent visualization openings 60, or the lower endwall 68 of a lower visualization opening and bottom end surface 38 ofplate 22. By engaging plate 22 along adjacent end walls or end surfaces,visualization opening 60 remains substantially unobstructed by holdinginstrument 500. In addition, the lateral profile of connecting system504 and holding system 506 can be minimized to minimize the lateralextent and obstruction of holding instrument 500 with bone engagingfastener holes 70, 71 and also to facilitate visualization along lateralside surfaces 40, 42.

Contacting surfaces 537, 547 can be provided with other surface profilesto conform to the surface of the plate to be engaged. For example,either or both of the contacting surfaces 537, 547 can be concavelycurved to conform to a convexly curved plate surfaces. Contactingsurface 537, 547 can be provided with teeth, ridges, barbs or othersurface features to enhance gripping with the plate.

In one embodiment, it is contemplated that movement of first holdingmember 530 in the direction of arrow 550 is effected by moving secondhandle portion 516 in the direction of arrow 552, thereby moving linkage514 distally in the direction of arrow 554 relative to first member 512and second member 513. Distal movement of linkage 514 positions cammingsurface 515 of linkage 514 in contact with an abutment portion 538 offirst holding member 530. Linkage 514 can thus, in addition to pushingon pin 533, push distally on abutment portion 538 of first holdingmember 530 to rotate it in the direction indicated by arrow 550. In oneembodiment, proximal portion 531 extend transversely to longitudinal;axis 505 to offset engagement member 539 from engagement member 541 whenholding members 530, 540 are moved to there clamped position. Thisprovides space for positioning of the portion of the plate between theadjacent end walls therebetween.

Holding member 530 includes an intermediate portion 529 between proximalportion 531 and engagement member 539. Holding member 540 includeintermediate portion 545 between engagement member 541 and receptacle549. Intermediate portions 529, 545 extending generally in the directionof longitudinal axis 505, and provide a gap or space between holdingmembers 530, 540 extending along longitudinal axis 505 to facilitateviewing of the plate portion clamped therebetween.

The clamping force applied to the plate clamped between holding members530, 540 can be maintained with locking system 508. To release theplate, locking system 508 is released so that handle portion 516 can bemoved in the direction opposite arrow 552 to separate first holdingmember 530 from second holding member 540. This movement of handleportion 516 pulls linkage 514 proximally to pivot first holding member530 in the direction opposite arrow 550 relative to second member 513. Aspring mechanism 560 can be provided between first handle portion 510and second handle portion 516 to bias holding system 506 toward thereleased position and facilitate release of the plate or implant clampedor engaged therebetween.

In the illustrated embodiment, locking system 508 includes a locking arm562 having a ratchet surface 564 located along one side thereof. Lockingarm 562 is pivotally attached to second handle portion 516, and extendsthrough a passage formed through first handle portion 510. Ratchetsurface 564 is moveable into engagement with one or more locking members566 on first handle portion 510. A grasping portion 568 facilitates thesurgeon in rotating locking arm 562 away from locking member 566 when itis desired to release the plate or implant secured in holding system506. It is contemplated that locking member 566 and ratchet surface 564can be configured to allow incremental movement of handle portion 516 inthe direction of arrow 552. Locking member 566 engages one or more ofthe teeth comprising ratchet surface 564, and then automatically lockssecond handle portion 516 in the moved position to prevent movement ofsecond handle portion 516 in the direction opposite arrow 552 unlesslocking arm 562 is released.

In one embodiment, holding instrument 500 has application with spinalplates to provide a low profile at the surgical site, facilitatingvisualization of the surgical site and minimizing obstruction of theholding instrument with other instruments and implants at the surgicalsite. Other applications of holding instrument 500 include surgicalprocedures for implanting other implants where visualization is desired.Connecting system 504 can include tubular elements, rod-like elements,linkages, elastically-deformable members, and articulating connectors,for example. Handle system 502 can include handles to facilitate thesurgeon's control of the depth, angular orientation and rotationalorientation of holding system 506 and the implant held thereby. Othersuitable examples of handle systems 502 include t-bars, pistol-grips,hooks, circular finger controls, co-axial shafts, and side-by-sideshafts. Lock system 508 includes any device or mechanism capable ofreleasably securing holding system 506 to the implant. Suitable examplesof locking system 508 include force-fit or wedge-type lockingmechanisms, pivoting lock mechanisms, rotating lock mechanisms, gearedlock mechanisms, etc.

Referring now to FIGS. 25-27, another embodiment holding instrumentincludes a mechanism for facilitating the placement drills, taps, and orbone engaging fasteners through the plate holes in the desired angularorientation. Holding instrument 500 is the same as holding instrument500 discussed above, except for the inclusion of guide mechanism 570 andthe alteration of the orientation of the locking system. Locking system588 includes a locking arm 589 having a ratchet surface 586 locatedalong one side thereof like locking arm 562. However, the locking arm589 is pivotally attached to first handle portion 510, and extendsthrough a passage formed through second handle portion 516. Ratchetsurface 586 is oriented upwardly along a concavely curved portion of thelocking arm, and biased into engagement with one or more locking members(not shown) on second handle portion 516. A distally extending graspingportion 587 facilitates the surgeon in rotating the locking arm awayfrom the locking member in second handle portion 516 when it is desiredto release the plate or implant secured in holding system 506. Anorientation such as that shown with locking system 508 can also be used.

A guide mechanism 570 can be permanently or releasably attached toconnecting system 504 of holding instrument 500. As shown in FIG. 27, acoupling mechanism 577 can be attached to the stationary second member513, and guide mechanism 570 can be attached, integrally formed, orotherwise secured to coupling mechanism 577. Guide mechanism 570 can beprovided with one or more guide members 572, 574 including passages 576,578 alignable with holes 70, 71, respectively, of plate 22. Passages576, 578 are sized so that a bone engaging fastener can be positionedtherethrough and guided to the proper location and orientation relativeto plate 22, such as shown in FIG. 27.

Connecting system 504 and holding system 506 are positionedsubstantially in alignment with longitudinal axis 21 of plate 22 so thatholes 70, 71 remain accessible by the surgeon through guide mechanism570. Holding system 506 grips or holds plate 22 along end surfaces orend walls oriented transversely to longitudinal axis 21 of plate 22. Thesurgeon can visualize the holes from either side of guide mechanism 570,and also from the cephalad and caudal directions, without holding system506 obstructing the surgeon's view.

As shown in FIG. 27, a bone engaging fastener 24, 25 can be positionedthrough hole 70, 71 of plate 22. A driving instrument 590 includes ashaft 592 slidably received in and guided by guide member 574 throughpassage 578 thereof. A tool engaging end 594 engages a tool recess inthe head of fastener 24, 25. Fastener 24, 25 is positioned into hole 70,71 along axis 72, 73 having an orientation with respect to plate 22 asdiscussed above. With holding system 506 engaged to plate 22, thecentral axis of passage 576, 578 is oriented in alignment with axis 72,73.

In the illustrated embodiment, second holding member 540 is angledrelative to proximal portion of second member 513 at an angle 543 sothat with holding member 540 oriented substantially perpendicularly toplate 22 connecting system 504 extends caudally or away from the upperend surface of plate 22. This locates actuating system 501 out of theway of the surgeon so that guide mechanism 570 is unobstructed. Inaddition, guide mechanism 570 can be mounted on connecting system 504 sothat the bone engaging fasteners are positioned along axis 72, 73 ofholes 70, 71. Other embodiments contemplate guide mechanism 570 mountedto place fasteners along other axes relative to plate 22.

Guide mechanism 570 can be permanently attached to connector system 504,or releasably attached thereto for interchangeability with other guidemechanisms that provide different angular orientations or to accommodateother instrument sizes and/or types. It is further contemplated thatholding instrument 500 can be provided without a guide mechanism, andthe drilling, tapping and/or fastener insertion is completed through theplate holes via freehand techniques or other guiding instruments.

Guide mechanism 570 can be used to guide self-drilling screws, such asbone engaging fastener 700 discussed above, that are driven directlyinto the underlying vertebrae or bone. Guide mechanism 570 can alsoreceive a sleeve, such as sleeve 595 in FIG. 25 to facilitatepreparation of the hole to receive bone engaging fasteners that requirepre-drilled and/or pre-tapped holes. Sleeve 595 includes a distalportion 596 positionable through the passage of one or both of the guidemembers 572, 574, and a proximal portion 596 that abuts the proximal endof the respective guide member 572, 574 to secure sleeve 595 thereto.Sleeve 595 can include one or more fingers 598 extending from a distalend of proximal portion 597 that is positionable in a notch 573 openingtoward the proximal end of the guide member, such as shown with respectto guide member 572. The interface between finger 598 and notch 573prevents sleeve 595 from rotating relative to guide member 572. Sleeve595 includes a central passage 599 extending therethrough sized toreceive and guide a drilling instrument through guide member 572 and theplate holes into the underlying bone. Sleeve 595 can then be removed,and self-tapping screws can then be inserted into the drilled holes.Guide members 572, 574 can also be used with or without a sleeve toguide a tapping instrument into drilled holes, and screws then insertedinto the drilled, tapped holes through the guide members. It is furthercontemplated that the bone engaging fasteners can be fixed ormulti-axial relative to the plate.

Referring now to FIGS. 28-30, another embodiment holding instrumentincludes a mechanism for facilitating the placement drills, taps, and orbone engaging fasteners through the plate holes in the desired angularorientation enhancing visualization of the placement. Holding instrument800 can be similar to holding instrument 500 discussed above, except forthe inclusion alignment mechanism 840 and the positioning of guidemechanism 870 relative thereto. Holding instrument 800 includes anactuating system 801 and a handle system 802. A connecting system 804 isoperable with handle system 803 to move holding system 806 between aposition engaged or clamped with the plate and a position released fromthe plate. Handle system 802 includes a first handle portion 810 and asecond handle portion 816 pivotally secured to a frame portion 811 offirst handle portion 810. Connecting system 804 includes a first member812 coupled at its proximal end to frame portion 811 of first handleportion 810, and a second member 813 coupled at its proximal end toframe portion 811 of first handle portion 810. Locking system 888 canmaintain the holding system 806 in a locked position with the plateengaged thereby.

Guide mechanism 870 can be permanently or releasably attached toconnecting system 804 of holding instrument 800 with a couplingmechanism, such as coupling mechanism 577 in FIG. 27. The couplingmechanism can be attached to the stationary second member 813, and guidemechanism 870 can be attached, integrally formed, or otherwise securedwith arms 882, 884 of the coupling mechanism. Guide mechanism 870 can beprovided with one or more guide members 872, 874 including passages 876,878 alignable with holes 70, 71, respectively, of plate 22. Passages876, 878 are sized so that a driving instrument or guide sleeve can bepositioned therethrough and guided along a desired orientation relativeto plate 22.

Holding instrument 800 further includes an alignment mechanism 840extending from holding system 806 that facilitates alignment of thedistal end of the driving instrument, drilling instrument, and/ortapping instrument with the plate holes. Holding system 806 can beconfigured as discussed above with respect to holding system 506, andincludes first and second holding members to firmly and releasably gripplate 22 therebetween. Alignment mechanism 840 permits guide mechanism870 to be positioned proximally along connecting system 804 away fromplate 22 so that the surgeon's view of the plate is further enhancedbetween alignment mechanism 840 and guide mechanism 870. Accordingly, aspace between alignment mechanism 840 and guide mechanism 870 can beprovided that only includes connecting system 804 with no devices orstructures extending laterally therefrom that obstruct the surgeons vieof the plate holes during fastener placement.

Alignment mechanism 840 includes a first alignment member 842 extendinglaterally from first holding member 830 of holding system 806, and asecond alignment member 844 extending laterally from first holdingmember 830 in a direction opposite first alignment member 842. Holdingmember 830 includes an engagement member 839 having a distal flange 832,a proximal flange 834, and a contacting surface 837 therebetween toreceive the wall of the plate. First and second alignment members 842,844 are offset proximally from proximal flange 834 for positioning alongan upper surface of the plate 22 adjacent the respective plate holes 70,71 when holding system 806 is engaged with the plate.

First alignment member 842 includes an arm with an end portion 848curved toward the second holding member of holding system 806. Analignment surface 846 extends along alignment member 842, and isalignable with a side of the adjacent plate hole so that a drivinginstrument or the like positioned along alignment surface 846 is alignedwith the center of the plate hole. Similarly, second alignment member844 includes an arm with an end portion 852 curved toward the secondholding member of holding system 806. An alignment surface 850 extendsalong alignment member 844, and is alignable with a side of the hole ofthe plate so that a driving instrument or the like positioned alongalignment surface 850 is aligned with the center of the plate hole. Thecurved end portions 848, 852 resist lateral movement of the drivingmember relative to alignment mechanism 840. Alignment members 842, 844are open along the side thereof oriented toward the second holdingmember to provide an unobstructed view of the holes 70, 71 of plate 22.

Connecting system 804 and holding system 806 are positionedsubstantially in alignment with longitudinal axis 21 of plate 22 so thatholes 70, 71 remain accessible by the surgeon through guide mechanism870 and alignment mechanism 840. Holding system 806 grips or holds plate22 along end surfaces or end walls oriented transversely to longitudinalaxis 21 of plate 22. Alignment members 842, 844 extend around a portionof holes 70, 71. With guide mechanism 870 offset along connecting system804 away from plate 22, the open sides of alignment members 842, 844permit the surgeon to visualize holes 70, 71 along a portion thereofopposite the portion occupied by alignment members 842, 844 withoutholding system 806 or alignment mechanism 840 obstructing the surgeon'sview.

Any of the bone engaging fasteners 24, 25, 700 can be positioned throughholes 70, 71 of plate 22 with a driving instrument slidably received inand guided by the respective guide member 872, 874 through passage 876,878 thereof. Alignment mechanism 840 facilitates the surgeon maintainingthe position of the distal end of the driving instrument relative to theplate while allowing visualization along the open side of the alignmentmembers 842, 844. With holding system 806 engaged to plate 22, thecentral axes of passages 876, 878 and the alignment surfaces 846, 850 ofalignment members 842, 844 are oriented relative to the plate to alignthe fastener and driving instrument with the corresponding hole axes 72,73.

Guide mechanism 870 can be permanently attached to connector system 804,or releasably attached thereto for adjustment, interchangeability withother guide mechanisms, or for removal by the surgeon if desired. It isfurther contemplated that holding instrument 800 can be provided withouta guide mechanism 870, and the drilling, tapping and/or fastenerinsertion is completed through the plate holes using alignment mechanism840. Alignment members 842, 844 can be integrally formed with firstholding member 830 as shown, or permanently or releasably attachedthereto. Alignment mechanism 840 could alternatively be provided on thesecond holding member so that the alignment members open toward firstholding member 830. It is further contemplated that alignment mechanism840 can be provided with a single alignment member.

Guide mechanism 870 and alignment mechanism 840 can be used to guideself-drilling screws, such as bone engaging fastener 700, that aredriven directly into the underlying vertebrae or bone. Guide mechanism870 and alignment mechanism 840 can also receive a sleeve therethroughto guide a drilling instrument through the plate holes. Self-tappingscrews can then be inserted into the drilled holes. Guide mechanism 870and alignment mechanism 840 can also be used to guide a tappinginstrument into drilled holes, and screws then inserted into thedrilled, tapped holes through the guide members. It is furthercontemplated that the bone engaging fasteners can be fixed ormulti-axial relative to the plate.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, and that all changes andmodifications that come within the spirit of the invention are desiredto be protected.

The invention claimed is:
 1. A spinal plate, comprising: an elongatebody including a length extending along a central longitudinal axis, thelength of the elongate body being adapted to span a space betweenadjacent vertebrae, the body including a first connection portionattachable to a first one of the adjacent vertebrae and a secondconnection portion attachable to a second one of the adjacent vertebrae,and an intermediate portion extending between the first and secondconnection portions, the first and second connection portions eachincluding spaced apart first and second openings and a countersunkportion positioned between the first and second openings, theintermediate portion including a visualization opening extendingtherethrough for visualizing the space when the plate is attached to theadjacent vertebrae, the visualization opening including at least oneconvexly curved side wall, the visualization opening and the countersunkportion being located along the central longitudinal axis; a pluralityof washers, one of the washers being disposed in each of the countersunkportions; and a plurality of bone screws, a respective one of the bonescrews extending through a respective one of the washers such that ahead of the bone screw removably engages an inner surface of the washer.2. A spinal plate as recited in claim 1, wherein the visualizationopening includes a second convexly curved side wall opposite the atleast one convexly curved side wall.
 3. A spinal plate as recited inclaim 1, wherein the plate includes an outer wall surface along theintermediate portion, the outer wall surface having a concave curvaturealong the convexly curved side wall of the visualization opening.
 4. Aspinal plate as recited in claim 1, wherein the visualization openingincludes an hourglass shape.
 5. A spinal plate as recited in claim 1,wherein the intermediate portion includes a first member along one sideof the visualization opening and a second member along the opposite sideof the visualization opening, the first and second members extendingbetween the first and second connection portions.
 6. A spinal plate asrecited in claim 1, wherein the first and second openings and thecountersunk portion are aligned along a transverse axis that extendsperpendicular to the central longitudinal axis.
 7. A spinal plate asrecited in claim 6, wherein the washer includes at least one cutout, thewasher being rotatable between a first orientation in which the cutoutis spaced apart from one of the first and second openings and a secondorientation in which at least a portion of the washer overlaps one ofthe first and second openings in a manner that prevents a fastenerdisposed in one of the first and second openings from backing out of oneof the first and second openings.
 8. A spinal plate as recited in claim1, wherein the intermediate portion includes a second visualizationopening that is aligned with the visualization opening along the centrallongitudinal axis, the second visualization opening being spaced apartfrom the visualization opening.
 9. A plating system, comprising: theplate of claim 1; and an instrument for holding the plate along thecentral longitudinal axis of the plate comprising: an actuating system,a connecting system extending proximally from the actuating system, anda holding system at a distal end of the connecting system operablycoupled to the actuating system with the connecting system, the holdingsystem including first and second holding members moveable in thedirection of the central longitudinal axis of the plate with theactuating portion between a release position and a clamping position toselectively engage and release the plate.
 10. A plating system asrecited in claim 9, further comprising a guide mechanism along theconnecting system and an alignment mechanism adjacent the holding systemand distal of the guide mechanism.
 11. A plating system as recited inclaim 9, wherein: the guide mechanism includes a first guide memberalong one side of the connecting system and a second guide member alongthe other side of the connecting system; and the holding system ismovable in a plane extending between the first and second guide members.12. A plating system as recited in claim 9, further comprising a lockingsystem at the actuating system to secure the holding mechanism in anyone of a number of clamping positions.
 13. A plating system as recitedin claim 9, wherein: the first holding member is pivotally coupled tothe second holding member and the second holding member is stationary;and the connecting system includes a first member and a second member,the second holding member forming a distal integral extension of thesecond member.
 14. A plating system as recited in claim 9, wherein: thefirst holding member is pivotally coupled to the second holding memberand the second holding member is stationary; and the connecting systemincludes a linkage movable relative to the second member with theactuating system, a distal end of the linkage being coupled to the firstholding member and the linkage being translatable relative to the secondmember to pivot the first holding member relative to the second member.15. A method for positioning a plate adjacent a spinal column of apatient, comprising: providing the plate of claim 1; accessing theadjacent vertebrae; holding the plate along the central longitudinalaxis of the plate with a holding instrument; and positioning the plateon the adjacent vertebrae.
 16. A method as recited in claim 15, whereinholding the plate includes holding the plate between an end wall of theplate and an end wall of a visualization opening extending through theplate.
 17. A method as recited in claim 15, further comprising insertinga fusion device between the adjacent vertebrae before positioning theplate.
 18. A method as recited in claim 17, further comprisingvisualizing the inserted fusion device through the visualizationopening.
 19. A method as recited in claim 15, further comprisingsecuring the plate to the adjacent vertebrae with the bone screws.
 20. Aspinal plate as recited in claim 1, wherein the countersunk portionseach include a threaded inner surface that engages a threaded outersurface of a respective one of the bone screws.